The effect of behavior and psychotropic drugs on acetylcholine (ACh) turnover in rat brain regions will be studied. Turnover of ACh will be measured in rats given labeled choline during memory consolidation and during the extinction of an appetitively motivated task in the hippocampus and caudate nucleus, both of which are implicated in learning and memory. Drugs that are known to influence these behaviors (amphetamine and drugs that influence the cholinergic nervous system) will be studied for their effects on ACh turnover during these behaviors in the hippocampus and caudate nucleus. The effect of lesions of the caudate nucleus on behavior, and ACh turnover in the hippocampus will also be studied. In addition psychotropic drugs that are known to influence monoaminergic systems and for which there is suggestive evidence of actions on the cholinergic systems will be studied for their effects on ACh turnover in cortex, hippocampus, midbrain, striatum, hypothalamus, medulla and cerebellum: these drugs are amphetamine, chlordiazepoxide, desipramine, tetrahydrocannabinol, lithium, haloperidol, chlorpromazine and amantadine. If a drug influences ACh turnover, experiments will be done to learn the site or sites of action of the drug by studying the uptake and all the metabolites of choline and by examining synaptosomes to learn which pool or pools of ACh is influenced by the drug and, if indicated, by measuring the activities of choline acetyltransferase and choline posphokinase. This work should show the role of the cholinergic nerve system in behavior and a mechanism of action of drugs that influence behavior.